100 Biologie. — Varietäten Descendenz, H5''briden. 



this spot and can be carried away by the wind — a mode of disper- 

 sal unique among the nearly 400 species of the genus Mesembnan- 

 themum. The plant was discovered in the Ceres Karoo by Capt. 

 Edward Aiston. Author's abstract. 



Collins, G. N., The origin of maize. (Journ. Washington Acad. 

 Sei. II. p. 520—530. Dec. 4. 1912.) 



"Maize originated as a hybrid between teosinte {Euchlaena 

 rnexicana) and an unknown grass belonging to the tribe Andropo- 

 goneae^\ Trelease. 



Davis, B. M., A much desired Oenothera. (PI. World. XVI. p 

 145-153. May 1913.) 



A request for material from the Southwest in the hope of 

 rediscovering what is held to be the original of '^Oenothera La- 

 rnarckianä'^ of the Dutch dunes. Trelease. 



Davis, B. M., Was Lamarck's evening primrose [Oenothera 

 Lamarckimia Seringe) a form of Oenothera grandißora Solan- 

 der? (Bull. Torr. Bot. Cl. XXXIX. p. 519-523. pl- 37-39. Nov. 1912.) 



The name '•^Oenothera Lamarckiana De Vries" is retained for 

 the basis of De Vries' cultures, which is held for a garden pro- 

 duct, the original Lamarckiana of Seringe being need for a form 

 of grandißora , and not at all the same unless the de Vriesian plant be 

 accepted as a hybrid between the latter and biennis. Trelease. 



Hume, M., On the Presence of Connecting Threads in 

 Graft Hybrids. (New Phyt. XII. 6. p. 216-221. 1 Textfig.Junel913.) 



The author gives a brief historical summary of the work done 

 on the genesis of connecting threads. A histological examination 

 was made of three graft hybrids: The results obtained for Cytisus 

 Adami confirmed those observed by Buder; connecting threads 

 were demonstratable in Solanum tubingense, but in no tissues in S. 

 Koelreuterianum. If Baur's hypothesis that graft hybrids are 

 really periclinal chimaeras be true, then connecting threads un- 

 doubtedly join genetically unrelated tissues. These threads arise 

 secondarih'^ and not from spindle fibres in the plants investigated, 

 and the connecting threads joining cells of genetically related and 

 cells of genetically unrelated tissues in the ground tissue appear 

 entirely the same. E. de Fraine. 



Regel, R., DiePflanzenzuchtungvomwissenschaft liehen 

 Standpunkte. (Bull, angew. Bot. V. 11. p. 425—622. Mit einer 

 Beilage, enthaltend 9 Tafel mit Erklärungen. St. Petersburg, Nov. 

 1912. Russisch und deutsch.) 



Die Gliederung der Arbeit ist folgende: 



Einleitung, Unveränderlichkeit der Erbeinheiten sowie die all- 

 gemeine Gültigkeit von Mendel's Spaltungsgesetz der Unterschei- 

 dungsmerkmale, Vorausbestimmung der Erblichkeit der Pflanzen- 

 formen, zur Frage über die Evolution der Organismen und über 

 die systematischen (taxonomischen) Einheiten, über die Grundprin- 

 zipien der Pflanzenzucht. Folgende Punkte seien hervorgehoben: 



